FORWARDING METHOD TO RETRIED SNOOP HIT, AND DATA PROCESSING SYSTEM

摘要

PROBLEM TO BE SOLVED: To obtain an improved method and device to process a snooping operation in a multi-processor system. SOLUTION: When a device which snoops around a system bus 122 detects an operation which requests data resident in a local memory in a certain coherency state, the device tries intervention. If this intervention is hindered by a second device which asserts retry, the device sets a flag which provides activity record information related to the intervention where a hindrance occurs. When the device asserts the intervention again and the snooped operation is retried again at the time of a following snoop hit to the same cache position, the device takes a measure to change the coherency state of a requested cache item to the final coherency state which is expected to be the result of the original operation requesting the cache item.